1. Field of the Invention
The present invention relates to liquid crystal display panels in which a substrate on which a metal-insulating film-metal diode (hereinafter referred to simply as "MiM diode") has been formed is utilized, and particularly to a construction of electrodes in the MiM diode.
2. Description of the Prior Art
As a method for increasing number of display picture elements in a liquid crystal display panel, such a method wherein active substrates fabricated by forming an active element such as transistor, diode or the like on a substrate constructing liquid crystal display panel are utilized has been proposed.
In view of manufacturing cost of liquid crystal display panel, when compared transistor type element with that of diode type, diode type is superior because of simplicity in manufacturing process of active elements. Among others, MiM diode system of Ta-Ta.sub.2 O.sub.5 -Cr construction is simpler than pn diode system in its manufacturing process of elements so that such system is promising.
For the sake of high density display, when a shape of picture elements is made small in a MiM-LCD the liquid crystal display panel of which is formed with a substrate provided with a MiM diode having Ta-Ta.sub.2 O.sub.5 -Cr construction, capacity of the crystal layer decreases, whilst capacity of the MiM diode increases relatively. Thus crosstalk between picture elements arises due to capacity coupling so that the display quality decreases remarkably.
As a method for reducing capacity of MiM diode, such a method in which width of metal electrodes in a MiM diode is narrowed to decrease area of the diode, whereby its capacity is reduced has been proposed (Reference for literature: Baraff et al., SjD Conference, 1980).
In the above method, it is required that the area of electrodes in the MiM diode is about 3 .mu.m.times.3 .mu.m for keeping the capacity of the MiM diode sufficiently small in order to drive picture elements having an area of 100 .mu.m.sup..quadrature.. For this purpose, it is necessary that Ta film etching of 3 .mu.m width as well as Cr film etching of 3 .mu.m width are carried out uniformly over the whole surface of its liquid crystal display panel substrate with favorable reproducibility. In the above process, however, since a resist used for etching has a very narrow width of 3 .mu.m, adhesion of the resist decreases so that the resist is separated. Hence there is such a disadvantage in the above process that it is very difficult to effect the etching over a wide area with uniformity as well as favorable reproducibility.